Table 1.
Compensatory sprouting and reinnervation after partial denervation of M1/3−/−, M2/4−/−, or M5−/− muscles
| Innervateda | Denervatedb | Reinnervatedc | Innervated with terminal sprouts (%) | NMJs with tSC bridges (%)d | Terminal sprouts (%) | Nodal sprouts (%) | |
|---|---|---|---|---|---|---|---|
| M1/3+/+ (2)e | 53 | 6 | 103 | 53.0 ± 7.6 | 28.9 ± 6.7 | 14.4 ± 4.2 | 90.5 ± 3.4 |
| M1/3−/− (2) | 44 | 4 | 86 | 45.6 ± 4.5 | 31.6 ± 1.7 | 11.5 ± 4.4 | 90.6 ± 2.0 |
| M2/4+/+ (5) | 222 | 23 | 131 | 59.2 ± 5.9 | 27.4 ± 1.3 | 39.6 ± 9.9 | 66.2 ± 6.8 |
| M2/4−/− (5) | 225 | 21 | 100 | 52.9 ± 6.4 | 27.6 ± 5.6 | 34.6 ± 3.2 | 61.3 ± 6.4 |
| M5+/+ (3) | 140 | 43 | 51 | 13.3 ± 7.3 | 12.7 ± 2.0 | 24.1 ± 14.7 | 75.9 ± 14.5 |
| M5−/− (2) | 10 | 47 | 55 | 38.8 ± 0.6 | 17.8 ± 0.3 | 9.1 ± 3.6 | 90.9 ± 0.3 |
Partially denervated M1/3−/−, M2/4−/−, and M5−/− EDL muscles exhibited similar reinnervation patterns as M1/3+/+, M2/4+/+, and M5+/+ muscles 14 d after L4 spinal root transection. Sprouting of remaining innervated endplates was similar, and the extent of reinnervation by terminal and nodal sprouts was not significantly different between +/+ and −/− muscles. Data are mean ± SEM.
aIntact NMJs spared by L4 transection.
bDenervated NMJs remaining completely devoid of axonal contact.
cDenervated NMJs reinnervated by nodal and/or terminal sprouts.
dThe percentage of all endplates examined (i.e., innervated and denervated) linked by tSC bridges.
eNumber of animals analyzed.